The current invention relates to the field of internally carbonated non-surfactant cleaning composition for cleaning textile fibers at ambient temperature. More specifically, this invention relates to non-surfactant compositions which are internally-carbonated by mixtures of an acid and two or more different compounds, which are carbonates, bicarbonates, or percarbonates, for the improved ability to clean fibers when the solution is at ambient temperature.
There are myriad types of cleaning compositions for cleaning textile fibers such as carpets, upholstery, drapery, and the like. Most of these cleaning compositions are based on soaps or detergents, both of which are generically referred to as "surfactants". By "detergent" is meant a synthetic amphipathic molecule having a large non-polar hydrocarbon end that is oil-soluble and a polar end that is water soluble. Soap is also an amphipathic molecule made up an alkali salt, or mixture of salts, of long-chain fatty acids wherein the acid end is polar or hydrophilic and the fatty acid chain is non-polar or hydrophobic. Detergents are further classified as non-ionic, anionic, or cationic. Anionic or nonionic detergents are the most common.
Surfactants, i.e. soaps and detergents, are formulated to loosen and disperse soil from textile fibers either physically or by chemical reaction. The soil can then be solubilized or suspended in such a manner that it can be removed from the fibers being cleaned. These surfactants function because the hydrophobic ends of the molecules coat or adhere to the surface of soils and oils and the water soluble hydrophilic (polar) ends are soluble in water and help to solubilize or disperse the soils and oils in an aqueous environment.
There are several problems associated with the use of surfactants for cleaning fibers such as those in carpeting and upholstery. First, large amounts of water are generally required to remove the surfactants and suspended or dissolved particles. This leads to long drying times and susceptibility to mildew. Second, surfactants generally leave an oily hydrophobic coating of the fiber surface. The inherent oily nature of the hydrophobic end of the surfactants causes premature resoiling even when the surfaces have a surfactant coating which is only a molecule thick. Third, surfactants can sometimes cause irritation or allergic reactions in people who are sensitive to these chemicals. Fourth, several environmental problems are associated with the use of soaps and detergents. Some are non-biodegradable and some contain excessive amounts of phosphates which are also environmentally undesirable. However, up until now, the inherent benefits of surfactants have out-weighed the disadvantages of resoiling, skin, membrane or eye irritation, allergic reactions and environmental pollution.
This concern for health and the environment has lead to a search for less toxic, more natural cleaning components. This search for carpet cleaning compositions that also have a balance of cleanability and resoiling resistance has resulted in compositions containing unnatural components that have a greater potential to cause allergenic reaction and other health and environmental problems. Normal soaps prepared from the base hydrolysis of naturally occurring fats and oils are not suitable for carpet cleaning because of the ability of their residues to attract soils. In order to make these residues less soil attracting, detergents are synthetically modified.
Several general problems occur in the use of any cleaning composition. One such general problem is that of oxidative yellowing, or "brown out" as it is commonly called. The usual conditions that increase the potential for brown out are a higher pH cleaner and/or prolonged drying times. Ordinarily the higher the concentration of solids in the cleaning composition, the greater the potential for this oxidative yellowing to produce a noticeable discoloration on carpets.
Another such general problem results from the use of a heated cleaning composition. Heat adversely affects a number of fabrics in residential or commercial use, that is, a heated cleaning solution may cause non-colorfast materials to fade, natural fibers to shrink, or glued fabrics to become unbonded to their substrate. Such materials would include cotton, wool, silk, linen, some rayons, and any of the many combinations thereof. Many organic or natural materials of the type used in the manufacture of oriental or middle eastern rugs and other hand crafted articles from other parts of the world contain dyes that do not have sufficient "set" to allow them to stand up under high temperature cleaners. Also, heated cleaning solutions require a significant amount of energy to heat the solution, as well as specialized equipment. Many residences do not have adequate electrical circuits to carry the amperage required by such equipment. Furthermore, the equipment itself tends to be bulky and difficult to use in a close residential environment, especially when the vendor must provide his own power arrangements; such arrangements generally use long hoses, gasoline generators, and the like. While an elevated temperature may assist in the cleaning of grease or oil stains in which the heat assists in dissolving the stain so that it can be picked up by the cleaning composition, most often the heat does more damage than not.
Carbonation of a cleaning composition has been proposed as a benign way to improve the mechanics of cleaning. A number of prior patents address themselves to this solution through the use of various combinations of carbonate and acid mixtures applied either under pressure or heat. U.S. Pat. No. 4,219,333 by Harris (the '333 patent), issued Aug. 26, 1980, teaches that detergent solutions, when carbonated, rapidly penetrate the textile fibers and, by benefit of the carbonation or effervescing action of the carbon dioxide, draw the suspended soil and oil particles to the surface of the fiber from which they can be removed. Carbonation is achieved by directly injecting carbon dioxide into the cleaning solution in a pressurized container such as a sprayer; internal carbonation is mentioned but not addressed to any extent.
U.S. Pat. No. 5,244,468 by Harris (the '468 patent), issued Sep. 14, 1993, teaches the use of self-carbonated, non-detergent, urea-containing compositions formed from the reaction between a single carbonate salt and a naturally occurring acid or acid forming material in the presence of urea or urea-like compounds. Carbon dioxide is provided both by the self-carbonating action and externally applied gas, i.e. carbon dioxide, which provides an effervescing action for lifting the soil and allowing the urea to clean and remove it.
U.S. Pat. No. 5,718,729 to Harris (the '729 patent), issued Feb. 17, 1998, teaches use of a heated carbonated solution containing urea which is applied to a textile fabric while retaining its carbonation. In achieving the self-carbonating action, the '729 Patent teaches the use of an acid forming material; a single carbonate, bicarbonate, or percarbonate alkaline salt; and urea, the resulting solution being applied in the presence of heat. Although a passing comment is made that mixtures of sodium carbonate and sodium bicarbonate are preferred for the alkaline salt, such a combination is not further taught, tested, nor claimed. Practice of the invention involves heating the cleaning composition to a temperature of at least 140 degrees Fahrenheit.
Although each of these prior art cleaning compositions has its advantages, it can be appreciated that none completely addresses all the problems described above. Thus, it can be seen that there is a need for a carbonated cleaning solution for both carpets and upholstery which has the following characteristics:
1. Improved cleaning properties over the carbonated solutions of the prior art. PA1 2. Ability to perform acceptably at ambient temperatures so as not to damage sensitive fabrics. PA1 3. Ability to perform acceptably at elevated temperatures for oil or grease stains requiring heat to assist in dissolving the stain. PA1 4. Composed of commercially inexpensive compounds. PA1 5. Non-toxic. PA1 6. Environmentally safe.